Pucch resource allocation and fallback operation

ABSTRACT

Systems and methods are disclosed herein that relate to resource allocation and/or fallback operation for an uplink control channel format, e.g., that supports feedback (e.g., Hybrid Automatic Repeat Request (HARQ) Acknowledgement (ACK) (HARQ-ACK) feedback) for up to a large number (e.g., thirty-two) carriers.

RELATED APPLICATIONS

This application claims the benefit of Patent Cooperation Treaty (PCT)patent application serial number PCT/CN2015/076176, filed Apr. 9, 2015,the disclosure of which is hereby incorporated herein by reference inits entirety.

TECHNICAL FIELD

The present disclosure relates to an uplink control channel in acellular communications network.

BACKGROUND Carrier Aggregation (CA)

The use of Third Generation Partnership Project (3GPP) Long TermEvolution (LTE) CA, which was introduced in Release 10 (Rel-10) andenhanced in Release 11 (Rel-11), offers a means to increase peak datarates, increase system capacity, and improve user experience byaggregating radio resources from multiple carriers that may reside inthe same band or different bands and, for the case of inter-band TimeDivision Duplexing (TDD) CA, may be configured with differentUplink/Downlink (UL/DL) configurations. In Release 12 (Rel-12), CAbetween TDD and Frequency Division Duplexing (FDD) serving cells isintroduced to support a User Equipment device (UE) connecting to the TDDand FDD serving cells simultaneously.

In Release 13 (Rel-13), Licensed Assisted Access (LAA) has attracted alot of interest in extending the LTE CA feature towards capturing thespectrum opportunities of unlicensed spectrum in the 5 Gigahertz (GHz)frequency band. Wireless Local Area Networks (WLANs) operating in the 5GHz band that are currently in the field already support a bandwidth of80 Megahertz (MHz). Further, support for a bandwidth of 160 MHz is tofollow in Wave 2 deployment of IEEE 802.11 ac. There are also otherfrequency bands, such as the 3.5 GHz frequency band, where aggregationof more than one carrier on the same band is possible, in addition tothe bands already widely in use for LTE. Enabling the utilization of atleast similar bandwidths for LTE in combination with LAA as IEEE 802.11ac Wave 2 will support calls for extending the LTE CA framework tosupport more than five carriers. The extension of the LTE CA frameworkbeyond five carriers was approved to be one work item for LTE Rel-13.The objective is to support up to thirty-two (32) carriers in both ULand DL.

One example of CA is illustrated in FIG. 1. As illustrated, multiplecarriers (referred to as Component Carriers (CCs)) are aggregated. Inthis example, a Primary Cell (PCell) and a Secondary Cell (SCell) areconfigured for a UE. The PCell includes, in this example, a UL CC and aDL CC (i.e., the PCell, in this example, is an FDD PCell), where the ULCC and the DL CC are, e.g., in a licensed frequency spectrum/band. TheSCell includes, in this example, a corresponding CC, which in thisexample is illustrated as a DL CC, where the CC of the SCell is, e.g.,in an unlicensed frequency spectrum/band. Such a configuration mayexist, for example, when using LAA. Note that the example of FIG. 1 isonly an example. For instance, while there are three CCs configured forthe UE in this example, as discussed above, there is a desire to supportup to thirty-two (32) CCs.

Compared to single-carrier operation, a UE operating with CA has toreport feedback for more than one DL CC. Meanwhile, a UE does not needto support DL and UL CA simultaneously. For instance, the first releaseof CA capable UEs in the market only supports DL CA but not UL CA. Thisis also the underlying assumption in the 3GPP Radio Access Network 4(RAN4) standardization. Therefore, an enhanced UL control channel, i.e.Physical UL Control Channel (PUCCH) format 3, was introduced for CAduring the Rel-10 timeframe. However, in order to support more CCs inRel-13, the UL control channel capacity becomes a limitation.

PUCCH Format 3

In LTE Release 8 (Rel-8), PUCCH format 1/1a/1b and PUCCH format 2/2a/2bare supported for Scheduling Request (SR), Hybrid Automatic RepeatRequest (HARQ) Acknowledgment (ACK) (HARQ-ACK), and periodic ChannelState Information (CSI) reporting. The PUCCH resource (i.e., theresource on which the PUCCH is transmitted by the UE) is represented bya single scalar index, from which the phase rotation and the orthogonalcover sequence (only for PUCCH format 1/1a/1b) are derived. The use of aphase rotation of a cell-specific sequence together with orthogonalsequences provides orthogonally between different terminals in the samecell transmitting PUCCH on the same set of resource blocks. In LTERel-10, PUCCH format 3 was introduced for carrier aggregation, whenthere are multiple downlink transmissions (either on multiple carriersor multiple downlink subframes in TDD) but single uplink (either singlecarrier or single uplink subframe) for HARQ-ACK, SR, and CSI feedback.

Similarly, the PUCCH format 3 resource is also represented by a singlescalar index, n_(PUCCH) ⁽³⁾, from which the orthogonal sequence(represented by a cyclic shift n_(oc,0) for a predefined base sequencefor slot 0 and a cyclic shift of n_(oc,0) for the predefined basesequence for slot 1) and the resource block number, m, can be derived. Alength-5 orthogonal sequence is applied for PUCCH format 3 to supportcode multiplexing within one resource block pair (see 3GPP TS 36.211V13.0.0) and a length-4 orthogonal sequence is applied for shortedPUCCH. Based on the scalar index, n_(PUCCH) ⁽³⁾, for the PUCCH format 3resource, the resource block of the PUCCH format 3 resource m isdetermined by the following

$m = \lfloor \frac{n_{{PUCCH}^{(3)}}}{N_{{SF},0}^{PUCCH}} \rfloor$

where N_(SF,0) ^(PUCCH) is the length of the orthogonal sequence forslot 0.

The orthogonal sequences applied for the two slots are derived by thefollowing:

n_(oc, 0) = n_(PUCCH)⁽³⁾mod N_(SF, 1)^(PUCCH)$n_{{oc},1} = \{ \begin{matrix}{( {3\; n_{{oc},0}} ){mod}\; N_{{SF},1}^{PUCCH}} & {{{if}\mspace{14mu} N_{{SF},1}^{PUCCH}} = 5} \\{n_{{oc},0}{mod}\; N_{{SF},1}^{PUCCH}} & {otherwise}\end{matrix} $

where N_(SF,1) ^(PUCCH) is the length of the orthogonal sequence forslot 1, where N_(SF,0) ^(PUCCH)=N_(SF,1) ^(PUCCH)=5 holds for both slotsin a subframe using normal PUCCH format 3 while N_(SF,0)^(PUCCH)=N_(SF,1) ^(PUCCH)=4 holds for the first slot and second slot ina subframe using shortened PUCCH format 3.

The PUCCH format 3 resource is determined according to higher layerconfiguration and a dynamic indication from the DL assignment. Indetail, the Transmit Power Control (TPC) field in the DL ControlInformation (DCI) format of the corresponding Physical DL ControlChannel (PDCCH)/Enhanced PDCCH (EPDCCH) is used to determine the PUCCHresource value from one of the four resource values configured by higherlayers, with the mapping defined in Table 1 below (see 3GPP TS 36.211V13.0.0). For FDD, the TPC field corresponds to the PDCCH/EPDCCH for thescheduled secondary serving cells. For TDD, the TPC field corresponds tothe PDCCH/EPDCCH for the PCell with a DL Assignment Indicator (DAI)value in the PDCCH/EPDCCH larger than ‘1.’ A UE assumes that the samePUCCH resource values are transmitted in each DCI format of thecorresponding PDCCH/EPDCCH assignments.

TABLE 1 PUCCH Resource Value for HARQ-ACK Resource for PUCCH Value of‘TPC command for PUCCH’ or ‘HARQ-ACK resource offset’ n_(PUCCH) ^((3,){tilde over (^(p))}⁾ ‘00’ The 1st PUCCH resource value configured by thehigher layers ‘01’ The 2^(nd) PUCCH resource value configured by thehigher layers ‘10’ The 3^(rd) PUCCH resource value configured by thehigher layers ‘11’ The 4^(th) PUCCH resource value configured by thehigher layers

New PUCCH Format to Support Up to 32 DL CCs

In 3GPP up to Rel-12, the maximum number of DL CCs is five (5). PUCCHformat 1b with channel selection and PUCCH format 3 are introduced forHARQ feedback and corresponding fallback operations are defined. As usedherein, fallback operation is the operation to fall back from one PUCCHformat to another PUCCH format (e.g., fall back from PUCCH format 3 toPUCCH format 1a/1b in the event that only two feedback bits arerequired). Fallback operation is beneficial not only from the HARQ-ACKperformance perspective but is also useful for a UE during the RRC(re)configuration period to avoid ambiguity between the eNB and the UE.However, in Rel-13, a maximum of 32 DL CCs can be configured for one UEand, therefore, a new PUCCH format will be introduced to carry moreHARQ-ACK bits due to the aggregation of up to 32 DL CCs.

There are four design options to support larger payload size on PUCCH:

-   -   Option 1: PUCCH format 3 with multiple Physical Resource Blocks        (PRBs)    -   Option 2: PUCCH format 3 with multiple Orthogonal Cover Codes        (OCCs)    -   Option 3: PUCCH format 3 with both multiple PRBs and OCCs    -   Option 4: PUSCH-like structure

PUCCH Format Fallback

PUCCH format 1 b with channel selection and PUCCH format 3 areintroduced in 3GPP Rel-10 to support HARQ-ACK feedback with CA. PUCCHfallback operation is also introduced for both PUCCH format 1b withchannel selection and PUCCH format 3 in a specific condition.

PUCCH format 1 b with channel selection involves configuring up to four(4) PUCCH format 1b resources (also referred to as “channels”). Theselection of one of these resources indicates some of the ACK/NegativeACK (NACK) information to be conveyed. There are mapping tablesspecified for the cases of two, three, or four ACK/NACK bits to definethe mapping of ACK/NACK combinations to the configured PUCCH resources.These tables are designed to support fallback to Rel-8 operation. Morespecifically, in the case of a single scheduled carrier, i.e. PCell, 1or 2 ACK/NACK bits will be transmitted by PUCCH format 1a/1b as inRel-8.

Similarly for PUCCH format 3, if no (E)PDCCH corresponding to PhysicalDownlink Shared Channel (PDSCH) on SCells is received and PDSCH isreceived on the PCell, 1 or 2 ACK/NACK bits will be transmitted by PUCCHformat 1a/1b as in Rel-8. For TDD, when PDSCH is only received from thePCell in one DL subframe where the DAI value is set to ‘1,’ PUCCH format1a/1b is used for HARQ-ACK transmission.

Problems

As discussed above, in 3GPP Rel-13, a maximum of thirty-two (32) DL CCscan be configured for one UE and, therefore, a new PUCCH format will beintroduced. Several design options are of great interest as describedabove. However, it is not clear how to do PUCCH resource allocation andfallback operation for the new PUCCH format, if the options mentionedabove are adopted. As such, there is a need for systems and methods forPUCCH resource allocation and fallback operation for the new PUCCHformat.

SUMMARY

Systems and methods are disclosed herein that relate to resourceallocation and/or fallback operation for an Uplink (UL) control channelformat, e.g., that supports feedback (e.g., Hybrid Automatic RepeatRequest (HARQ) Acknowledgement (ACK) (HARQ-ACK) feedback) for up to alarge number (e.g., thirty-two) carriers. In some embodiments, a methodof operation of a wireless device in a cellular communications networkto transmit UL control information for one or more carriers on a ULcontrol channel comprises transmitting a UL control channel transmissionusing a first UL control channel format if a first set of one or moreconditions for the first UL control channel format is satisfied. Themethod further comprises transmitting the UL control channeltransmission using a second UL control channel format if the first setof one or more conditions for the first UL control channel format is notsatisfied but a second set of one or more conditions for the second ULcontrol channel format is satisfied. The method further comprisestransmitting the UL control channel transmission using a third ULcontrol channel format if both the first set of one or more conditionsfor the first UL control channel format and the second set of one ormore conditions for the second UL control channel format are notsatisfied. In this manner, fallback operation is provided for the thirdUL control channel format, which may be a new or enhanced controlchannel format that supports feedback for up to a large number (e.g.,thirty-two) of carriers.

In some embodiments, the cellular communications network is a ThirdGeneration Partnership Project (3GPP) network, the first UL controlchannel format is format 1a/1b, and the second UL control channel formatis format 3.

In some embodiments, the third UL control channel format is a UL controlchannel format that uses a Physical UL Shared Channel (PUSCH) structure.In other embodiments, the third UL control channel format is a ULcontrol channel format that uses legacy format 3 over multiple PhysicalResource Blocks (PRBs), legacy format 3 over a single PRB with multipleOrthogonal Cover Codes (OCCs), legacy format 3 over multiple PRBs withmultiple OCCs, a modified format 3 with Tail-Biting Convolutional Code(TBCC) over multiple PRBs, a modified format 3 with TBCC over a singlePRB with multiple OCCs, or a modified format 3 with TBCC over multiplePRBs with multiple OCCs.

In some embodiments, the second set of one or more conditions for thesecond UL control channel format comprises a condition that a requirednumber of feedback bits for the UL control channel transmission is lessthan or equal to a threshold, M₂.

In some embodiments, the threshold, M₂, is equal to 22.

In some embodiments, the first set of one or more conditions for thefirst UL control channel format comprises a condition that a requirednumber of feedback bits for the UL control channel transmission is lessthan or equal to a threshold, M₁. Further, in some embodiments, thethreshold, M₁, is equal to 2 and the threshold, M₂, is equal to 22.

In some embodiments, the first set of one or more conditions for thefirst UL control channel format further comprises a condition thatfeedback bits are required only for a Primary Cell (PCell) of thewireless device. Further, in some embodiments, the threshold, M₁, isequal to 2. In some embodiments, the threshold, M₂, is equal to 22.

In some embodiments, the first set of one or more conditions for thefirst UL control channel format comprise: (a) a condition that feedbackbits are required only for a PCell of the wireless device and (b) arequired number of feedback bits for the UL control channel format isless than or equal to a threshold, M₁. Further, in some embodiments, thethreshold, M₁, is equal to 2.

In some embodiments, the wireless device is configured with a FrequencyDivision Duplexing (FDD) PCell according to a Carrier Aggregation (CA)scheme in which the UL control channel is transmitted on the FDD PCellof the wireless device, and the first set of one or more conditions forfallback to format 1a/1b comprises: (a) a condition that no Downlink(DL) control channel corresponding to a DL shared channel on anySecondary Cells (SCells) of the wireless device is received and (b) acondition that a DL shared channel is received on the FDD PCell of thewireless device.

In some embodiments, the wireless device is configured with a TimeDivision Duplexing (TDD) PCell according to a CA scheme in which the ULcontrol channel is transmitted on the TDD PCell of the wireless device,and the first set of one or more conditions for fallback to format 1a/1bcomprises: (a) a condition that no DL control channel corresponding to aDL shared channel on any SCells of the wireless device is received and(b) a condition that a DL shared channel is received on the TDD PCell inonly one DL subframe where a DL Assignment Indicator (DAI) value is setto “1.”

In some embodiments, the wireless device is configured with a FDD or TDDPCell according to a CA scheme in which the UL control channel istransmitted on the PCell of the wireless device, and the second set ofone or more conditions for fallback to format 3 comprises: (a) acondition that the wireless device receives a Physical Downlink SharedChannel (PDSCH) only on cells within a segment of less than or equal toM₂ feedback bits in a sequence of N possible feedback bits where N>M₂and (b) a condition that no DL control channel is received by thewireless device on any other cells.

In some embodiments, the wireless device is configured with a FDDPrimary Secondary Cell (pSCell) in a cell group according to a CA schemein which the UL control channel is transmitted on the FDD pSCell, wherethe FDD pSCell can be either a PCell of the wireless device or one ofone or more SCells of the wireless device, and the first set of one ormore conditions for fallback to format 1a/1b comprises: (a) a conditionthat no DL control channel corresponding to a DL shared channel on anySCells in a cell group is received and (b) a condition that a DL sharedchannel is received on the FDD pSCell.

In some embodiments, the wireless device is configured with a TDD pSCellin a cell group according to a CA scheme in which the UL control channelis transmitted on the TDD pSCell, where the TDD pSCell can be either aPCell of the wireless device or one of one or more SCells of thewireless device, and the first set of one or more conditions forfallback to format 1a/1b comprises: (a) a condition that no DL controlchannel corresponding to a DL shared channel on any SCells in a cellgroup is received and (b) a condition that a DL shared channel isreceived on the TDD pSCell in only one DL subframe where a DAI value isset to “1.”

In some embodiments, the wireless device is configured with a FDD or TDDpSCell in a cell group according to a CA scheme in which the UL controlchannel is transmitted on the pSCell, where the pSCell can be either aPCell of the wireless device or one of one or more SCells of thewireless device, and the second set of one or more conditions forfallback to format 3 comprises: (a) a condition that DL shared channelsare received by the wireless device on one or more SCells in a cellgroup that correspond to a segment of less than or equal to M₂ feedbackbits in a sequence of N possible feedback bits, where N>M₂ and (b) acondition that no DL control channel is received by the wireless deviceon any other SCells in the cell group.

In some embodiments, the wireless device is configured with a FDD pSCellaccording to a CA scheme in which the UL control channel is transmittedon the FDD pSCell, where the FDD pSCell is a PCell of the wirelessdevice, and the first set of one or more conditions for fallback toformat 1a/1b comprises: (a) a condition that no DL control channelcorresponding to a DL shared channel on any SCells in a cell group isreceived and (b) a condition that a DL shared channel is received on theFDD pSCell.

In some embodiments, the wireless device is configured with a TDD pSCellaccording to a CA scheme in which the UL control channel is transmittedon the TDD pSCell, where the TDD pSCell is a PCell of the wirelessdevice, and the first set of one or more conditions for fallback toformat 1a/1b comprises: (a) a condition that no DL control channelcorresponding to a DL shared channel on any SCells in a cell group isreceived and (b) a condition that a DL shared channel is received on theTDD pSCell in only one DL subframe where a DAI value is set to “1.”

Embodiments of a wireless device enabled to operate in a cellularcommunications network to transmit UL control information for one ormore carriers on a UL control channel are also disclosed. In someembodiments, the wireless device comprises one or more transmitters, oneor more processors, and memory containing instructions that areexecutable by the one or more processors whereby the wireless device isoperable to: transmit, via the one or more transmitters, a UL controlchannel transmission using a first UL control channel format if a firstset of one or conditions for the first UL control channel format issatisfied; transmit, via the one or more transmitters, the UL controlchannel transmission using a second UL control channel format if thefirst set of one or more conditions for the first UL control channelformat is not satisfied but a second set of one or more conditions forthe second UL control channel format is satisfied; and transmit, via theone or more transmitters, the UL control channel transmission using athird UL control channel format if both the first set of one or moreconditions for the first UL control channel format and the second set ofone or more conditions for the second UL control channel format are notsatisfied.

In other embodiments, a wireless device is adapted to perform any of theembodiments of the method of operation of a wireless device describedherein.

In other embodiments, a wireless device enabled to operate in a cellularcommunications network to transmit UL control information for one ormore carriers on a UL control channel comprises a UL control channeltransmission module operable to: transmit a UL control channeltransmission using a first UL control channel format if a first set ofone or conditions for the first UL control channel format is satisfied;transmit the UL control channel transmission using a second UL controlchannel format if the first set of one or more conditions for the firstUL control channel format is not satisfied but a second set of one ormore conditions for the second UL control channel format is satisfied;and transmit the UL control channel transmission using a third ULcontrol channel format if both the first second of one or moreconditions for the first UL control channel format and the second set ofone or more conditions for the second UL control channel format are notsatisfied.

In other embodiments, a wireless device enabled to operate in a cellularcommunications network to transmit UL control information for one ormore carriers on a UL control channel comprises: means for transmittinga UL control channel transmission using a first UL control channelformat if a first set of one or conditions for the first UL controlchannel format is satisfied; means for transmitting the UL controlchannel transmission using a second UL control channel format if thefirst set of one or more conditions for the first UL control channelformat is not satisfied but a second set of one or more conditions forthe second UL control channel format is satisfied; and means fortransmitting the UL control channel transmission using a third ULcontrol channel format if both the first second of one or moreconditions for the first UL control channel format and the second set ofone or more conditions for the second UL control channel format are notsatisfied.

In some embodiments, a non-transitory computer readable medium storingsoftware instructions that when executed by one or more processors of awireless device cause the wireless device to: transmit a UL controlchannel transmission using a first UL control channel format if a firstset of one or conditions for the first UL control channel format issatisfied; transmit the UL control channel transmission using a secondUL control channel format if the first set of one or more conditions forthe first UL control channel format is not satisfied but a second set ofone or more conditions for the second UL control channel format issatisfied; and transmit the UL control channel transmission using athird UL control channel format if both the first set of one or moreconditions for the first UL control channel format and the second set ofone or more conditions for the second UL control channel format are notsatisfied.

In some embodiments, a computer program comprises instructions which,when executed on at least one processor, cause the at least oneprocessor to carry out the method of operation of a wireless deviceaccording to any of the embodiments described herein. In someembodiments, a carrier is provided, wherein the carrier contains theaforementioned computer program, wherein the carrier is one of anelectronic signal, an optical signal, a radio signal, or a computerreadable storage medium.

According to one aspect of the present disclosure, methods of resourceallocation and fallback operation for the new Physical UL ControlChannel (PUCCH) format in 3GPP Release 13 (Rel-13) are proposed.

The resource allocation and fallback solutions in the present disclosureenable the compatibility with existing PUCCH format(s). It is beneficialnot only from HARQ-ACK performance perspective but also useful forwireless devices (e.g., User Equipment devices (UEs)) during the RRC(re)configuration period to avoid ambiguity between the eNB and the UE.

Those skilled in the art will appreciate the scope of the presentdisclosure and realize additional aspects thereof after reading thefollowing detailed description of the embodiments in association withthe accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawing figures incorporated in and forming a part ofthis specification illustrate several aspects of the disclosure, andtogether with the description serve to explain the principles of thedisclosure.

FIG. 1 illustrates one example of Carrier Aggregation (CA);

FIG. 2 illustrates one example of a cellular communications network inwhich resource allocation and fallback operation for a new PhysicalUplink Control Channel (PUCCH) format are implemented according to someembodiments of the present disclosure;

FIG. 3 is a flow chart that illustrates the operation of the wirelessdevice to transmit PUCCH using the new PUCCH format according to someembodiments of the present disclosure;

FIG. 4 is a flow chart that illustrates a fallback procedure for the newPUCCH format according to some embodiments of the present disclosure;

FIG. 5 is a flow chart that illustrates a fallback procedure for the newPUCCH format according to some embodiments of the present disclosure;

FIG. 6 illustrates one example segmentation of feedback bits for the newPUCCH format;

FIGS. 7A and 7B illustrate a fallback procedure performed by thewireless device for the new PUCCH format according to some embodimentsof the present disclosure;

FIG. 8 is a flow chart that illustrates a decision process for decidingwhether to fall back from the new PUCCH format to PUCCH format 3according to some embodiments of the present disclosure;

FIG. 9 is a flow chart that illustrates process for deciding whether tofall back from the new PUCCH format to PUCCH format 3 according to someembodiments of the present disclosure;

FIG. 10 illustrates another example segmentation of feedback bits forthe new PUCCH format;

FIG. 11 illustrates another example segmentation of feedback bits forthe new PUCCH format;

FIGS. 12A and 12B illustrate a fallback procedure performed by thewireless device for the new PUCCH format according to some embodimentsof the present disclosure;

FIG. 13 is a flow chart that illustrates a decision process for decidingwhether to fall back from the new PUCCH format to PUCCH format 3according to some embodiments of the present disclosure;

FIG. 14 is a flow chart that illustrates a decision process for decidingwhether to fall back from the new PUCCH format to PUCCH format 3according to some other embodiments of the present disclosure;

FIGS. 15A and 15B illustrate a fallback procedure performed by thewireless device for the new PUCCH format according to some otherembodiments of the present disclosure;

FIG. 16 illustrates the operation of the base station and the wirelessdevice of FIG. 2 according to some embodiments of the presentdisclosure;

FIGS. 17 and 18 are schematic block diagrams of a base station accordingto some embodiments of the present disclosure; and

FIGS. 19 and 20 are schematic block diagrams of a wireless deviceaccording to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The embodiments set forth below represent information to enable thoseskilled in the art to practice the embodiments and illustrate the bestmode of practicing the embodiments. Upon reading the followingdescription in light of the accompanying drawing figures, those skilledin the art will understand the concepts of the disclosure and willrecognize applications of these concepts not particularly addressedherein. It should be understood that these concepts and applicationsfall within the scope of the disclosure and the accompanying claims.

Radio Node:

As used herein, a “radio node” is either a radio access node or awireless device.

Radio Access Node:

As used herein, a “radio access node” is any node in a radio accessnetwork of a cellular communications network that operates to wirelesslytransmit and/or receive signals. Some examples of a radio access nodeinclude, but are not limited to, a base station (e.g., an enhanced orevolved Node B (eNB) in a Third Generation Partnership Project (3GPP)Long Term Evolution (LTE) network), a high-power or macro base station,a low-power base station (e.g., a micro base station, a pico basestation, a home eNB, or the like), and a relay node.

Core Network Node:

As used herein, a “core network node” is any type of node in a CoreNetwork (CN). Some examples of a core network node include, e.g., aMobility Management Entity (MME), a Packet Data Network (PDN) Gateway(P-GW), a Service Capability Exposure Function (SCEF), or the like.

Wireless Device:

As used herein, a “wireless device” is any type of device that hasaccess to (i.e., is served by) a cellular communications network bywirelessly transmitting and/or receiving signals to a radio accessnode(s). Some examples of a wireless device include, but are not limitedto, a User Equipment device (UE) in a 3GPP LTE network and a MachineType Communication (MTC) device.

Network Node:

As used herein, a “network node” is any node that is either part of theradio access network or the CN of a cellular communicationsnetwork/system.

Note that the description given herein focuses on a 3GPP cellularcommunications system and, as such, 3GPP LTE terminology or terminologysimilar to 3GPP LTE terminology is oftentimes used. However, theconcepts disclosed herein are not limited to a 3GPP system.

Note that, in the description herein, reference may be made to the term“cell;” however, particularly with respect to Fifth Generation (5G)concepts, beams may be used instead of cells and, as such, it isimportant to note that the concepts described herein are equallyapplicable to both cells and beams.

As discussed above, in 3GPP Release 13 (Rel-13), the Carrier Aggregation(CA) feature is extended such that a maximum of thirty-two (32) Downlink(DL) Component Carriers (CCs) can be configured for one UE. Therefore, anew Physical Uplink Control Channel (PUCCH) format that supports HybridAutomatic Repeat Request (HARQ) Acknowledgement (ACK) (HARQ-ACK)feedback for up to thirty-two (32) CCs will be introduced. Severaldesign options are of great interest, as described in the Background.Systems and methods for PUCCH resource allocation and fallback operationfor the new PUCCH format are disclosed herein. Notably, the new PUCCHformat is referred to herein as PUCCH format 4 for clarity and ease ofdiscussion. However, PUCCH format 4 is only the name used for the newPUCCH format herein. The new PUCCH format may be given a different namein the 3GPP standards.

In this regard, FIG. 2 illustrates one example of a cellularcommunications network 10 in which PUCCH format 4 resource allocationand fallback operations are implemented according to some embodiments ofthe present disclosure. In this example, the cellular communicationsnetwork 10 is an LTE network (e.g., a License Assisted Access LTE(LAA-LTE) network or a LTE in Unlicensed Spectrum (LTE-U) network) thatincludes a base station 12, which in LTE is referred to as an eNB, thatserves multiple cells 14, each operating on a different carrier. In thisparticular example, the base station 12 serves up to thirty-two (32)cells, which are referred to generally as cells 14-1 through 14-32,operating on carriers F1 through F32, respectively. In some embodiments,the carriers F1 through F32 are all in a licensed frequency spectrum.However, in other embodiments, some of the carriers F1 through F32 arein a licensed frequency spectrum (i.e., in one or more licensedfrequency bands) while other ones of the carriers F1 through F32 are inan unlicensed frequency spectrum (i.e., in one or more unlicensedfrequency bands), which would be the case when the cellularcommunications network 10 is an LAA-LTE network. In other embodiments,all of the carriers F1 through F32 are in an unlicensed frequencyspectrum (i.e., in one or more unlicensed frequency bands). Note thatwhile thirty-two cells 14 are illustrated in this example, the basestation 12 may serve any number of cells 14 (e.g., any number of one upto 32 cells or potentially even more than 32 cells, depending on, e.g.,the particular implementation). In this particular example, a wirelessdevice 16, which in LTE terminology is referred to as a UE, is served bythe base station 12. It should also be noted that while the cells 14 areall provided by the same base station 12 in this example, the presentdisclosure is not limited thereto. The cells 14 may be provided by anynumber of one or more radio access nodes.

The base station 12, or eNB 12, and the wireless device 16, or UE 16,operate according to a CA scheme in which up to, in this example,thirty-two (32) carriers (referred to as CCs, can be configured for thewireless device 16. In this example, the cell 14-1 is configured as aPrimary Cell (PCell) of the wireless device 16 and, as such, the carrierF1 is referred to herein as a Primary CC (PCC). One or more of the othercells 14-2 through 14-32 are configured as Secondary Cells (SCells) ofthe wireless device 16 and, as such, the respective carriers arereferred to herein as Secondary CCs (SCCs).

The wireless device 16 transmits Uplink Control Information (UCI) suchas Scheduling Requests (SRs), periodic Channel State Information (CSI),and HARQ-ACKs using PUCCH. When operating according to a DL CA scheme,the wireless device 16 is able to transmit HARQ-ACKs for up to eight (8)cells 14 when using conventional PUCCH formats. The new PUCCH format(referred to herein as PUCCH format 4) extends the PUCCH capacity tosupport HARQ-ACKs for up to thirty-two (32) cells 14.

I. Design Options for PUCCH Format 4

Currently, there are four design options for PUCCH format 4, namely:

-   -   Option 1: PUCCH format 3 (legacy or modified) with multiple        Physical Resource Blocks (PRBs)    -   Option 2: PUCCH format 3 (legacy or modified) with multiple        Orthogonal Cover Codes (OCCs)    -   Option 3: PUCCH format 3 (legacy or modified) with both multiple        PRBs and multiple OCCs    -   Option 4: PUCCH format having a Physical Uplink Shared Channel        (PUSCH)-like structure        Each of these options along with embodiments of resource        allocation for PUCCH format 4 for these design options are        described in detail below.

II. Resource Allocation for PUCCH Format 4

The following discussion provides embodiments of resource allocation foreach of the different PUCCH format 4 design options.

A. Resource Allocation for PUCCH Format 4 Design Option 1

Design option 1 for PUCCH format 4 is to use legacy PUCCH format 3 or amodified PUCCH format 3 (e.g., PUCCH format 3 with Tail-BitingConvolutional Code (TBCC)) on multiple PRBs to carry more HARQ-ACK bitsthan is possible with the current, or legacy, PUCCH format 3 (i.e., tocarry a number of HARQ-ACK bits that exceeds the capacity of legacyPUCCH format 3).

i. Alternative 1: Use Legacy PUCCH Format 3

In some embodiments, PUCCH format 4 uses the legacy PUCCH format 3 onmultiple PRBs. The number of PRBs needed for PUCCH format 4 is denotedas N_(PUCCH4) and calculated by

$N_{{PUCCH}\; 4} = \lceil \frac{O_{ACK}}{q} \rceil$

where N_(ACK) is the number of HARQ-ACK bits in total and q is themaximum number of HARQ-ACK bits that can be carried by one PRB usingPUCCH format 3, i.e., q is equal to 22. O_(ACK) can be determined basedon the number of scheduled carriers, the number of activated carriers,or the number of configured carriers. Moreover, the number of transportblocks on each carrier and whether HARQ-ACK bundling is applied is alsotaken into account.

In a manner similar to PUCCH format 3, the PUCCH resource for PUCCHformat 4, which is denoted N_(PUCCH) ⁽⁴⁾, is determined according tohigher layer configuration and a dynamic indication from the DLassignment. In some embodiments, based on the PUCCH format 4 resourceN_(PUCCH) ⁽⁴⁾, the resource block numbers of the PUCCH format 4 resourcem is determined by the following:

m = ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋, ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋ +     1, …  , ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋ + N_(PUCCH 4) − 1

where, as mentioned previously, N_(SF,0) ^(PUCCH) denotes the length ofthe orthogonal sequence in the first slot (i.e., slot 0).

In some other embodiments, the resource allocation of PUCCH format 4 isdefined directly based on the first configured PUCCH format 4 resourceand the length of the orthogonal sequence for the first slots. Thewireless device 16 would determine, when transmitting, how manyresources it should allocate depending on the number of PUCCH format 4resources required, which is denoted by N_(PUCCH4). Each resource isdefined as follows

m = ⌊n_(PUCCH(z))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋  z = 0, 1, …  , N_(PUCCH 4) − 1

The orthogonal sequence applied for the two slots is similar to theapproach for PUCCH format 3. In one example, the same OCC applies formultiple PRBs. In another example, different OCCs apply for differentPRBs following a predefined rule. A principle is that the OCC used forthe resource block number with the lowest index should follow exactlythe same approach for PUCCH format 3. This is to enable fallbackoperation.

In some other embodiments, the wireless device 16 is configured by thebase station 12 with a set of PUCCH format 4 resources. Each resource isthen individually determined, which could for example be as follows:

m = ⌊n_(PUCCH(0))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋, ⌊n_(PUCCH(1))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋, …  , ⌊n_(PUCCH(N_(PUCCH) − 1))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋

The wireless device 16 would only use up to N_(PUCCH4) number ofresources, although it is possible to configure the wireless device 16with the maximum number of resources.

ii. Alternative 2: Use Modified PUCCH Format 3

In some embodiments, PUCCH format 4 uses a modified PUCCH format 3(e.g., PUCCH format 3 with TBCC) on multiple PRBs. In some embodiments,the number of PRBs needed for PUCCH format 4 is denoted as N_(PUCCH4)and calculated by

${N_{{PUCCH}\; 4}\lceil \frac{O_{ACK} - 22}{q} \rceil} + 1$

where O_(ACK) is the number of HARQ-ACK bits in total and q is themaximum number of HARQ-ACK bits that can be carried by one PRB usingmodified PUCCH format 3 (e.g., PUCCH format 3 with TBCC). In the formulaabove, 22 reflects the maximum number of HARQ-ACK bits already supportedby legacy PUCCH format 3.

In some other embodiments, the number of PRBs needed for PUCCH format 4is denoted as N_(PUCCH4) and calculated by

${N_{{PUCCH}\; 4}\lceil \frac{O_{ACK} - q}{q} \rceil} + 1$

where O_(ACK) is the number of HARQ-ACK bits in total and q is themaximum number of HARQ-ACK bits that can be carried by one PRB usingmodified PUCCH format 3 (e.g., PUCCH format 3 with TBCC).

In a manner similar to PUCCH format 3, the PUCCH resource for PUCCHformat 4, which is denoted N_(PUCCH) ⁽⁴⁾, is determined according tohigher layer configuration and a dynamic indication from the DLassignment. Based on the PUCCH format 4 resource N_(PUCCH) ⁽⁴⁾, theresource block numbers of the PUCCH format 4 resource m is determined bythe following

m = ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋, ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋ +       1, …  , ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋ + N_(PUCCH 4) − 1

The orthogonal sequence applied for the two slots is similar to theapproach for PUCCH format 3. In one example, the same OCC applies formultiple PRBs. In another example, different OCCs apply for differentPRBs following a predefined rule. A principle is that the OCC used forthe resource block number with the lowest index should follow exactlythe same approach for PUCCH format 3. This is to enable fallbackoperation.

B. Resource Allocation for PUCCH Format 4 Design Option 2

Design option 2 for PUCCH format 4 is to use legacy PUCCH format 3 or amodified PUCCH format 3 (e.g., PUCCH format 3 with TBCC) with multipleOCCs (on a single PRB) to carry more HARQ-ACK bits than is possible withthe current, or legacy, PUCCH format 3 (i.e., to carry a number ofHARQ-ACK bits that exceeds the capacity of legacy PUCCH format 3).

i. Alternative 1: Use Legacy PUCCH Format 3

In some embodiments, PUCCH format 4 uses the legacy PUCCH format 3 withmultiple OCCs. The number of OCCs needed for PUCCH format 4 is denotedas C_(PUCCH4) and calculated by

$C_{{PUCCH}\; 4} = \lceil \frac{O_{ACK}}{q} \rceil$

where O_(ACK) is the number of HARQ-ACK bits in total and q is themaximum number of HARQ-ACK bits that can be carried by one PRB and oneOCC using PUCCH format 3, i.e., q is equal to 22. C_(PUCCH4) is equal toor less than N_(SF,1) ^(PUCCH).

The orthogonal sequences applied for the two slots are defined, withrespect to a predefined base sequence, by cyclic shifts n_(oc,0),n_(oc,0)+1, . . . , n_(oc,0)+C_(PUCCH4)−1 and n_(oc,1), n_(oc,1)+1, . .. , n_(oc10)+C_(PUCCH4)−1 derived by the following

n_(oc, 0) = n_(PUCCH)⁽⁴⁾mod N_(SF, 1)^(PUCCH)$n_{{oc},1} = \{ \begin{matrix}{( {3n_{{oc},0}} ){mod}\; N_{{SF},1}^{PUCCH}} & {{{if}\mspace{14mu} N_{{SF},1}^{PUCCH}} = 5} \\{n_{{oc},0}{mod}\; N_{{SF},1}^{PUCCH}} & {otherwise}\end{matrix} $

where N_(SF,0) ^(PUCCH) is the length of the orthogonal sequence forslot 0 and N_(SF,1) ^(PUCCH) is the length of the orthogonal sequencefor slot 1, where N_(SF,0) ^(PUCCH)=N_(SF,1) ^(PUCCH)=5 holds for bothslots in a subframe using normal PUCCH format 4 while N_(SF,0)^(PUCCH)=N_(SF,1) ^(PUCCH)=4 holds for the first slot and the secondslot in a subframe using shortened PUCCH format 4.

In a manner similar to PUCCH format 3, the PUCCH resource for PUCCHformat 4, which is denoted as n_(PUCCH) ⁽⁴⁾, is determined according tohigher layer configuration and a dynamic indication from the DLassignment. Based on the PUCCH format 4 resource as n_(PUCCH) ⁽⁴⁾, theresource block number of the PUCCH format 4 resource m is determined bythe following

m = ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋

ii. Alternative 2: Use Modified PUCCH Format 3

In some embodiments, PUCCH format 4 uses a modified PUCCH format 3(e.g., PUCCH format 3 with TBCC) with multiple OCCs. In someembodiments, the number of OCCs needed for PUCCH format 4 is denoted asC_(PUCCH4) and calculated by

$C_{{PUCCH}\; 4} = {\lceil \frac{O_{ACK} - 22}{q} \rceil + 1}$

where O_(ACK) is the number of HARQ-ACK bits in total and q is themaximum number of HARQ-ACK bits that can be carried by one PRB with oneOCC using modified PUCCH format 3 (e.g., PUCCH format 3 with TBCC).C_(PUCCH4) is equal to or less than N_(SF,1) ^(PUCCH).

In some other embodiments, the number of PRBs needed for PUCCH format 4is denoted as C_(PUCCH4) and calculated by

$C_{{PUCCH}\; 4} = {\lceil \frac{O_{ACK} - q}{q} \rceil + 1}$

where O_(ACK) is the number of HARQ-ACK bits in total and q is themaximum number of HARQ-ACK bits that can be carried by one PRB with oneOCC using modified PUCCH format 3 (e.g., PUCCH format 3 with TBCC).C_(PUCCH4) is equal to or less than N_(SF,1) ^(PUCCH).

The orthogonal sequences applied for the two slots are defined, withrespect to a predefined base sequence, by cyclic shifts n_(oc,0),n_(oc,0)+1, . . . , n_(oc,0)+C_(PUCCH4)−1 and n_(oc,1), n_(oc,1)+1, . .. , n_(oc10)+C_(PUCCH4)−1 derived by the following

n_(oc, 0) = n_(PUCCH)⁽⁴⁾mod N_(SF, 1)^(PUCCH)$n_{{oc},1} = \{ \begin{matrix}{( {3n_{{oc},0}} ){mod}\; N_{{SF},1}^{PUCCH}} & {{{if}\mspace{14mu} N_{{SF},1}^{PUCCH}} = 5} \\{n_{{oc},0}{mod}\; N_{{SF},1}^{PUCCH}} & {otherwise}\end{matrix} $

where N_(SF,0) ^(PUCCH) is the length of the orthogonal sequence forslot 0 and N_(SF,1) ^(PUCCH) is the length of the orthogonal sequencefor slot 1, where N_(SF,0) ^(PUCCH)=N_(SF,1) ^(PUCCH)=5 holds for bothslots in a subframe using normal PUCCH format 4 while N_(SF,0)^(PUCCH)=N_(SF,0) ^(PUCCH)=4 holds for the first slot and the secondslot in a subframe using shortened PUCCH format 4.

In a manner similar to PUCCH format 3, the PUCCH resource for PUCCHformat 4, which is denoted as n_(PUCCH) ⁽⁴⁾, is determined according tohigher layer configuration and a dynamic indication from the DLassignment. Based on the PUCCH format 4 resource n_(PUCCH) ⁽⁴⁾, theresource block number of the PUCCH format 4 resource m is determined bythe following

m = ⌊n_(PUCCH)⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋

C. Resource Allocation for PUCCH Format 4 Design Option 3

Design option 3 for PUCCH format 4 is to use legacy PUCCH format 3 or amodified PUCCH format 3 (e.g., PUCCH format 3 with TBCC) on multiplePRBs with multiple OCCs to carry more HARQ-ACK bits than is possiblewith the current, or legacy, PUCCH format 3 (i.e., to carry a number ofHARQ-ACK bits that exceeds the capacity of legacy PUCCH format 3).

The total number of OCCs for PUCCH format 4 is denoted as C_(PUCCH4) andcalculated by

$C_{{PUCCH}\; 4} = \lceil \frac{O_{ACK}}{q} \rceil$

where O_(ACK) is the number of HARQ-ACK bits in total and q is themaximum number of HARQ-ACK bits that can be carried by one PRB and oneOCC using PUCCH format 3, i.e., q is equal to 22. C_(PUCCH4) is largerthan n_(SF,1) ^(PUCCH) in this case.

The number of PRBs for PUCCH format 4 is denoted as N_(PUCCH4) andcalculated by

$N_{{PUCCH}\; 4} = \lceil \frac{C_{{PUCCH}\; 4}}{N_{{SF},1}^{PUCCH}} \rceil$

D. Resource Allocation for PUCCH Format 4 Design Option 4

Design option 4 for PUCCH format 4 is to use a PUSCH structure for PUCCHformat 4, i.e., one Demodulation Reference Signal (DMRS) per slot andremaining Resource Elements (REs) are used for transmitting the UCIinformation. The coding of UCI information bits could be Turbo code orconvolutional code. The resource allocation for this option could be ahigh layer signaling or added in the DCI message for the DL assignment.

III. PUCCH Transmission

FIG. 3 is a flow chart that illustrates the operation of the wirelessdevice 16 to transmit PUCCH using PUCCH format 4 according to someembodiments of the present disclosure. As illustrated, the wirelessdevice 16 determines a resource allocation for a PUCCH format 4transmission, as described above (step 100). As discussed above, PUCCHformat 4 may use the legacy or modified PUCCH format 3 over multiplePRBs, with multiple OCCs (over a single PRB), or with both multiple PRBsand multiple OCCs. In each of these options, the manner in which theresource allocation is determined is described above. The wirelessdevice 16 transmits a PUCCH format 4 transmission using the determinedresource allocation (step 102).

IV. Fallback Operation for PUCCH Format 4

The following discussion provides embodiments of fallback operation forPUCCH format 4 design options. A flow chart that illustrates a fallbackprocedure is illustrated in FIG. 4. As illustrated, the wireless device16 determines whether to fall back to PUCCH format 1a/1b (step 200). Ifso, rather than transmitting using PUCCH format 4, the wireless device16 transmits a PUCCH transmission in PUCCH format 1a/1b (step 202). Ifthe wireless device 16 determines that fallback to PUCCH format 1a/1b isnot appropriate, the wireless device 16 determines whether to fall backto PUCCH format 3 (step 204). If so, the wireless device 16 transmits aPUCCH transmission in PUCCH format 3 (step 206). Otherwise, if fallbackto PUCCH format 3 is also not appropriate, the wireless device 16transmits a PUCCH transmission in the new PUCCH format (again referredto herein as PUCCH format 4) (step 208).

FIG. 5 is a flow chart that illustrates a fallback procedure inaccordance with some embodiments of the present disclosure. In general,fallback decisions are made based on the number of feedback bits thatare required in a subframe to provide the desired feedback. Asillustrated, the wireless device 16 determines whether the number ofrequired feedback bits for the subframe is less than or equal to a firstthreshold, M₁ (step 300). In some particular embodiments, the firstthreshold, M₁, is 2. If the number of required feedback bits for thesubframe is less than or equal to the first threshold, M₁, then thewireless device 16 decides to fall back to PUCCH format 1a/1b and, assuch, transmits a PUCCH transmission for the subframe in PUCCH format1a/1b (step 302). If the required number of feedback bits for thesubframe is greater than the first threshold, M₁, but less than or equalto a second threshold, M₂ (step 304; YES), the wireless device 16decides to fall back to PUCCH format 3 and, as such, transmits a PUCCHtransmission for the subframe in PUCCH format 3 (step 306). In someparticular embodiments, the second threshold, M₂, is 22. If the requirednumber of feedback bits for the subframe is greater than the secondthreshold, M₂ (step 304; NO), the wireless device 16 decides that thereshould be no fallback and, as such, transmits a PUCCH transmission forthe subframe in PUCCH format 4 (step 308).

Notably, while FIG. 5 focuses on the condition of the number of feedbackbits being less than the first threshold, M₁, for fallback to PUCCHformat 1a/1b, as discussed below, one or more additional conditions mayalso be required before fallback to PUCCH format 1a/1b. For example, asdiscussed below, if PUCCH is provided on the PCell, the additionalcondition(s) may include, e.g.:

-   -   For a Frequency Division Duplex (FDD) PCell, a condition that no        (Enhanced) Physical DL Control Channel ((E)PDCCH) corresponding        to Physical DL Shared Channel (PDSCH) on SCells is received and        a condition that PDSCH is received on the PCell; and    -   For a Time Division Duplex (TDD) PCell, a condition that no        (E)PDCCH corresponding to PDSCH on SCells is received and a        condition that PDSCH is received on the PCell in only one DL        subframe where the Downlink Assignment Indicator (DAI) value is        set to ‘1.’        Other example conditions that may also be considered in addition        to the number of required feedback bits for fallback to PUCCH        format 1a/1b are described below. In a similar manner, one or        more additional conditions for fallback to PUCCH format 3 may        also be considered.

In other words, the process of FIG. 5 can be described as follows. Ifthe required feedback bits in a subframe are included in a predefinedsegmentation with length M₁ bits, referred to herein as a firstpredefined segmentation, format 1a/1b is used. For example, in Release10 (Rel-10), the predefined segmentation corresponds to the first 2bits. As an example, M₁=2. Otherwise, if the required feedback bits in asubframe are included in a predefined segmentation with length M₂ bits,referred to herein as a second predefined segmentation, format 3 isused. As one example, the second predefined segmentation corresponds tothe first M₂=22 bits. Otherwise, a new format such as format 4 is used.

One example is shown in FIG. 6. Assuming the feedback bits (i.e., thetotal number N of feedback bits to accommodate feedback for up to 32cells) are a_(n)(n=0, . . . , N−1), the first segmentation includesfeedback bits a₀, a₁, and the second segment includes feedback bits a₀,a₁, . . . , a₂₀, a₂₁. In case only a₀, a₁, or both a₀ and a₁ arerequired for feedback, format 1a/1b is used. In case some (or all) ofbits a₀, . . . , a₂₁ are required for feedback in addition to a₀, or a₁or a₀,a₁, and no other feedback is required, format 3 is used.Otherwise, a new format such as format 4 is used.

In the following section, detailed conditions on the fallback operationfor various embodiments of the present disclosure are provided. Ingeneral, these various conditions are indicative of whether the feedbackbits are required only for the PCell or the PUCCH SCell in a cell group,and/or whether the number of required feedback bits is less than orequal to M₁, greater than M₁ but less than or equal to M₂, or greaterthan M₂ and, as such, are indicative of whether fallback operationshould be used and, if so, which PUCCH format to use for the fallbackoperation.

A. PUCCH on PCell i. Fall Back to PUCCH Format 1a/1b

In some embodiments, the fallback of PUCCH format 4 is PUCCH format1a/1b for some specific conditions listed below:

-   -   For a Frequency Division Duplex (FDD) PCell, if no (Enhanced)        Physical DL Control Channel ((E)PDCCH) corresponding to Physical        DL Shared Channel (PDSCH) on SCells is received and PDSCH is        received on the PCell, fall back to PUCCH format 1a/1b.        -   In this case, only a₀ or a₀, a₁ is required.    -   For a Time Division Duplex (TDD) PCell, if no (E)PDCCH        corresponding to PDSCH on SCells is received and PDSCH is        received on the PCell in only one DL subframe where the Downlink        Assignment Indicator (DAI) value is set to ‘1,’ fall back to        PUCCH format 1a/1b.        Otherwise, PUCCH format 4 will fall back to format 3 when some        other specific conditions are satisfied, which are described in        the “Fall back to PUCCH format 3” section.

In this regard, FIGS. 7A and 7B illustrate a fallback procedureperformed by the wireless device 16 according to some embodiments of thepresent disclosure. As illustrated, PUCCH is transmitted on the PCell14-1 of the wireless device 16. In order to determine whether PUCCHformat 4 should fall back to some other PUCCH format, the wirelessdevice 16 determines whether the PCell 14-1 is on an FDD carrier or aTDD carrier (step 400). If the PCell 14-1 of the wireless device 16 ison an FDD carrier, the wireless device 16 determines whether: (a) thewireless device 16 has received no (E)PDCCH corresponding to PDSCH onany SCells 14 of the wireless device 16 and (b) the wireless device 16has received a PDSCH on the PCell 14-1 (step 402). If the conditions instep 402 are true, then the wireless device 16 decides that fallback toPUCCH format 1a/1b is appropriate and, as such, transmits PUCCHaccording to format 1a/1b (step 404).

Returning to step 400, if the PCell 14-1 of the wireless device 16 isnot an FDD cell (i.e., if the PCell 14-1 of the wireless device 16 is aTDD cell), the wireless device 16 determines whether: (a) the wirelessdevice 16 has received no (E)PDCCH corresponding to PDSCH on any SCells14 of the wireless device 16 and (b) the wireless device 16 has receiveda PDSCH on the PCell 14-1 in only one DL subframe where the DAI value isset to “1” (step 406). If the conditions in step 406 are true, then thewireless device 16 decides that fallback to PUCCH format 1a/1b isappropriate and, as such, transmits PUCCH according to format 1a/1b(step 404).

If the conditions in step 402 are false for a FDD PCell or if theconditions in step 406 are false for a TDD PCell, the wireless device 16determines whether one or more conditions for fallback to PUCCH format 3are satisfied (step 408). While any suitable conditions may be used,some example conditions for fallback to PUCCH format 3 for the casewhere PUCCH is transmitted on the PCell 14-1 are described in thefollowing section. If the condition(s) for fallback to PUCCH format 3 issatisfied, the wireless device 16 decides that fallback to PUCCH format3 is appropriate and, as such, transmits PUCCH according to format 3(step 410). However, if the condition(s) for fallback to PUCCH format 3is not satisfied, the wireless device 16 decides that fallback to PUCCHformat 3 is not appropriate and, as such, transmits PUCCH according tothe new format, which again is referred to herein as format 4 (step412).

ii. Fallback to PUCCH format 3

If the condition of falling back to PUCCH format 1a/1b is not satisfied,PUCCH format 4 may fall back to format 3. The conditions to fall back toformat 3 are included in the following embodiments.

In some embodiments, if PDSCH is received on one or more SCells withpredefined cell indices and no (E)PDCCH corresponding to PDSCH on otherSCells is received, PUCCH format 4 falls back to PUCCH format 3. Thisdecision process, which may be viewed as one example embodiment of step408 of FIG. 7B, is illustrated in FIG. 8. As illustrated, the wirelessdevice 16 determines whether: (a) the wireless device 16 received PDSCHon one or more SCells 14 with predefined indices and (b) the wirelessdevice 16 received no (E)PDCCH corresponding to PDSCH on any otherSCells 14 (step 500). If these conditions are satisfied, the wirelessdevice 16 decides to fall back to PUCCH format 3 (step 502). Otherwise,the wireless device 16 decides to use the new PUCCH format (format 4)(step 504).

As one example of the predefined cell indices, the cell indices 1-4 maybe set as the predefined cell indices. Given this condition, if all theCCs are FDD carriers, the second segmentation includes HARQ-ACK feedbackbits a₀, a₁, . . . , a₉ without appending of a SR. If all the CCs areTDD carriers, the second segmentation includes HARQ-ACK feedback bitsa₀, a₁, . . . , a₁₉ without appending of a SR. If the CCs are a mixtureof FDD and TDD carriers, the second segmentation includes HARQ-ACKfeedback bits a₀, a₁, . . . , a_(M-1), where M is determined by thecarrier configuration of cell indices 1-4. Note that 1 bit SR can beappended on HARQ-ACK feedback and sent on the same PUCCH format.

In some embodiments, the following steps could be used to determine thecondition for the format 3 fallback. These steps are illustrated in theflow chart of FIG. 9.

-   -   Obtaining each CC configuration and the capacity of PUCCH format        3 which can be used for the HARQ-ACK feedback (step 600).    -   Selecting the feedback bits to form the segmentation, the size        of the segmentation is based on the obtained capacity (step        602).    -   Deciding the CC and subframes associated with the formed        segmentation based on the information of the CC configurations        and PUCCH configuration (step 604).        If PDSCH is received only on the cells associated with the        formed segmentation and no (E)PDCCH corresponding to PDSCH on        other cells is received (step 606; YES), the wireless device 16        decides to fall back to PUCCH format 3 (step 608). Otherwise        (step 606; NO), the wireless device 16 decides to use the new        PUCCH format (i.e., format 4) (step 610). The process of FIG. 9        can be viewed as one embodiment of step 408 of FIG. 7B.

In this embodiment, the associated cell indices may be different ondifferent Uplink (UL) subframes to determine the fallback to PUCCHformat 3. As one example, in case of TDD CA, assuming there are 6 CCsand the TDD configuration for the 6 CCs are:

-   -   CC0: UL-DL configuration 1 (primary carrier)    -   CC1: UL-DL configuration 0    -   CC2: UL-DL configuration 1    -   CC3: UL-DL configuration 1    -   CC4: UL-DL configuration 1    -   CC5: UL-DL configuration 1        The UL-DL configuration is defined in 3GPP TS 36.211 V13.0.0. In        this case, the cell indices associated with the formed        segmentation for different subframes are:    -   In case the PUCCH is transmitted on subframe 7 or subframe 2,        the cell indices associated with the PUCCH on these subframes        are 0, 1, 2, 3, 4, 5    -   In case the PUCCH is transmitted on subframe 8 or subframe 3,        the cell indices associated with the PUCCH on these subframes        are 0, 2, 3, 4, 5, 6

In some embodiments, a plurality of segmentations may be formed. Eachsegmentation is allocated on one PUCCH format 3 resource. The PUCCHformat 3 resource may be overlapped with the PUCCH format 4 resource.Further, the PUCCH format 3 resource may be derived from the resourceallocation for PUCCH format 4. If all the PDSCHs are received only onthe cells corresponding to one segmentation, the PUCCH format will fallback to format 3, and the resource for the fallback is given by theallocated PUCCH format 3 resource associated with the segmentation. Asone example shown in FIG. 10, assuming that there are 20 FDD carriers,the second segment including the feedback bits corresponding to CC 0˜9,and the third segment including the feedback bits corresponding to CC10˜19, assume the PUCCH resource

m = ⌊n_(PUCCH(0))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋, ⌊n_(PUCCH(1))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋

is allocated for PUCCH format 4. In this case:

-   -   If PDSCH is received only on the cells with cell indices 0˜9 and        no (E)PDCCH corresponding to PDSCH on other cells is received,        format 4 will fall back to PUCCH format 3 and the resource        n_(PUCCH(0)) ⁽⁴⁾/N_(SF,0) ^(PUCCH) will be used for the PUCCH        format 3.    -   If PDSCH is received only on the cells with cell indices 10˜19        and no (E)PDCCH corresponding to PDSCH on other cells is        received, format 4 will fall back to PUCCH format 3 and the        resource n_(PUCCH(1)) ⁽⁴⁾/N_(SF,0) ^(PUCCH) will be used for the        PUCCH format 3.    -   Otherwise, PUCCH format 4 will be used.

In some embodiments, a plurality of segmentations may be formed. Eachsegmentation is allocated one PUCCH format 3 resource. If the PDSCHs arereceived on the cells associated with multiple segmentations, the PUCCHformat may fall back to multiple PUCCH format 3 transmissions and theresources for the fallback are given by the allocated PUCCH format 3resources associated with these segmentations. As one example shown inFIG. 11, assuming there are 20 FDD carriers, the second segmentincluding the feedback bits corresponding to CC 0˜9, and the thirdsegment including the feedback bits corresponding to CC 10˜19, assumethe PUCCH resource

m = ⌊n_(PUCCH(0))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋, ⌊n_(PUCCH(1))⁽⁴⁾/N_(SF, 0)^(PUCCH)⌋

is allocated for PUCCH format 4. In this case:

-   -   If PDSCH is received only on the cells with cell indices 0˜9 and        no (E)PDCCH corresponding to PDSCH on other cells is received,        format 4 will fall back to PUCCH format 3 and the resource        n_(PUCCH(0)) ⁽⁴⁾/N_(SF,0) ^(PUCCH) will be used for the PUCCH        format 3.    -   If PDSCH is received only on the cells with cell indices 10˜19        and no (E)PDCCH corresponding to PDSCH on other cells is        received, format 4 will fall back to PUCCH format 3 and the        resource n_(PUCCH(1)) ⁽⁴⁾/N_(SF,0) ^(PUCCH) will be used for the        PUCCH format 3.    -   If PDSCH is received on some cells with cell indices 0˜9 and        some cells with cell indices 10˜19, and no (E)PDCCH        corresponding to PDSCH on other cells is received, format 4 will        fall back to two PUCCH format 3 transmissions, where the        resource n_(PUCCH(0)) ⁽⁴⁾/N_(SF,0) ^(PUCCH) and the resource        n_(PUCCH(1)) ⁽⁴⁾/N_(SF,0) ^(PUCCH) will be used for respective        PUCCH format 3 transmissions.    -   Otherwise, PUCCH format 4 will be used.

B. PUCCH on SCell

In case there is PUCCH transmitted on SCells 14 of the wireless device16, there may exist multiple PUCCH cell groups. In each PUCCH cellgroup, there may exist multiple DL carriers. For PUCCH on SCells 14,there are multiple realization methods for PUCCH transmission:

-   -   PUCCH is transmitted on one SCell 14 configured by higher-layer        signaling to carry PUCCH for SCells 14 in the PUCCH cell group.    -   PUCCH is transmitted on the PCell 14-1 for SCells 14 in the        PUCCH cell group.    -   PUCCH is transmitted on SCell-only (i.e., no PUCCH on the PCell        14-1). Note that, based on current agreements, PUCCH on        SCell-only (i.e., no PUCCH on the PCell 14-1) is not supported        in Rel-13, but may be re-discussed in a future release.

For the first two realizations, PUCCH is transmitted on both the PCell14-1 and an SCell 14. For the third realization, there is no PUCCH onthe PCell 14-1. For the first two realizations, the fallback conditionis similar. For the third realization, the fallback condition for format1a/1b is slightly different. The following sections provide details onthe fallback solution for the first two realizations and the thirdrealization, respectively.

i. PUCCH is Transmitted on Both PCell and SCell

Here, Primary SCell (pSCell) is used to denote the cell which transmitsPUCCH in the PUCCH cell group. If PUCCH is transmitted on the PCell forSCells in the PUCCH cell group, the pSCell is the PCell. Otherwise,pSCell is one of the SCells, and therefore can be also referred to as aPUCCH-SCell.

In some embodiments, all of the description above in the section “PUCCHon PCell” can be applied for each PUCCH cell group. The fallbackoperation may be independent between cell groups.

As one example, for PUCCH format 1a/1b fallback, the specific conditionsare listed below:

-   -   For FDD pSCell, if no (E)PDCCH corresponding to PDSCH on SCells        in the PUCCH cell group is received and PDSCH is received on        pSCell, fall back to PUCCH format 1a/1b.    -   For TDD pSCell, if no (E)PDCCH corresponding to PDSCH on SCells        in the PUCCH cell group is received and PDSCH is received on        pSCell in only one DL subframe where the DAI value is set to        ‘1,’ fall back to PUCCH format 1a/1b.

In this regard, FIGS. 12A and 12B illustrate a fallback procedureperformed by the wireless device 16 according to some embodiments of thepresent disclosure. This fallback procedure implements the conditionsfor fallback to PUCCH format 1a/1b provided above. As illustrated, PUCCHis transmitted on both the PCell 14-1 and an SCell 14. In order todetermine whether PUCCH format 4 should fall back to some other PUCCHformat, the wireless device 16 determines whether the pSCell, which canbe the PCell 14-1 or one of the SCells 14 of the wireless device 16, fora PUCCH cell group for such a PUCCH transmission is desired is on an FDDcarrier or a TDD carrier (step 700). If the pSCell of the wirelessdevice 16 is on an FDD carrier, the wireless device 16 determineswhether: (a) the wireless device 16 has received no (E)PDCCHcorresponding to PDSCH on any SCells 14 of the wireless device 16 in thePUCCH cell group and (b) the wireless device 16 has received a PDSCH onthe pSCell of the PUCCH cell group (step 702). If the conditions in step702 are true, then the wireless device 16 decides that fallback to PUCCHformat 1a/1b is appropriate and, as such, transmits PUCCH according toformat 1a/1b (step 704).

Returning to step 700, if the pSCell of the wireless device 16 for thePUCCH cell group is not an FDD cell (i.e., if the pSCell of the wirelessdevice 16 is a TDD cell), the wireless device 16 determines whether: (a)the wireless device 16 has received no (E)PDCCH corresponding to PDSCHon any SCells of the wireless device 16 in the PUCCH cell group and (b)the wireless device 16 has received a PDSCH on the pSCell in only one DLsubframe where the DAI value is set to “1” (step 706). If the conditionsin step 706 are true, then the wireless device 16 decides that fallbackto PUCCH format 1a/1b is appropriate and, as such, transmits PUCCHaccording to format 1a/1b (step 704).

If the conditions in step 702 are false for a FDD pSCell or if theconditions in step 706 are false for a TDD pSCell, the wireless device16 determines whether one or more conditions for fallback to PUCCHformat 3 are satisfied (step 708). While any suitable conditions may beused, some example conditions for fallback to PUCCH format 3 for thecase where PUCCH is transmitted on the PCell 14-1 are described below.If the condition(s) for fallback to PUCCH format 3 is satisfied, thewireless device 16 decides that fallback to PUCCH format 3 isappropriate and, as such, transmits PUCCH according to format 3 (step710). However, if the condition(s) for fallback to PUCCH format 3 is notsatisfied, the wireless device 16 decides that fallback to PUCCH format3 is not appropriate and, as such, transmits PUCCH according to the newformat, which again is referred to herein as format 4 (step 712).

For fallback to PUCCH format 3, the embodiments described above in thesection “PUCCH on PCell” may be updated into:

Embodiment #1

-   -   If PDSCH is received on one or more SCells in the PUCCH cell        group with predefined cell indices and no (E)PDCCH corresponding        to PDSCH on other SCells in the PUCCH cell group is received,        fall back to PUCCH format 3. This is illustrated in FIG. 13.        This process may be viewed as one example embodiment of step 708        of FIG. 12B. As illustrated, the wireless device 16 determines        whether: (a) the wireless device 16 received PDSCH on one or        more SCells in the PUCCH cell group with predefined indices        and (b) the wireless device 16 received no (E)PDCCH        corresponding to PDSCH on any other SCells in the PUCCH cell        group (step 800). If these conditions are satisfied, the        wireless device 16 decides to fall back to PUCCH format 3 (step        802). Otherwise, the wireless device 16 decides to use the new        PUCCH format (format 4) (step 804).

Embodiment #2

-   -   In some embodiments, the following steps could be used to        determine the condition for the format 3 fallback. These steps        are illustrated in the flow chart of FIG. 14.        -   Obtain each CC configuration in the PUCCH cell group and the            capacity of PUCCH format 3 which can be used for the            HARQ-ACK feedbacks (step 900).        -   Select the HARQ-ACK feedback bits to form the segmentation,            the size of the segmentation is based on the obtained            capacity (step 902).        -   Decide the CC and subframes associated with the formed            segmentation based on the information for the CC            configurations and PUCCH configuration (step 904).        -   If PDSCH is received only on the cells associated with the            formed segmentation in the PUCCH cell group and no (E)PDCCH            corresponding to PDSCH on other cells in the PUCCH cell            group is received (step 906; YES), fall back to PUCCH format            3 (step 908). Otherwise (step 906; NO), decide to use the            new PUCCH format (i.e., PUCCH format 4) (step 910).

Embodiment #3

-   -   In some embodiments, a plurality of segmentations may be formed        in each PUCCH cell group.

Not all the embodiments in the section “PUCCH on PCell” are elaboratedin this section. Similar principles can be applied to the embodimentswhich are not repeated here.

ii. PUCCH is Transmitted on SCell Only (i.e., No PUCCH on PCell)

For this case, the fallback to format 1a/1b described above for thePUCCH on PCell and PUCCH on PCell and SCell is modified into:

-   -   For an FDD PCell, if no (E)PDCCH corresponding to PDSCH on        SCells is received and PDSCH is received on the PCell, fall back        to PUCCH format 1a/1b. The PUCCH format 1a/1b is transmitted on        the SCell UL carrier.    -   For a TDD PCell, if no (E)PDCCH corresponding to PDSCH on SCells        is received and PDSCH is received on the PCell in only one DL        subframe where the DAI value is set to ‘1,’ fall back to PUCCH        format 1a/1b. The PUCCH format 1a/1b is transmitted on the SCell        UL carrier.    -   For a FDD pSCell, if no (E)PDCCH corresponding to PDSCH on other        cells in the PUCCH cell group is received and PDSCH is received        on the pSCell, fall back to PUCCH format 1a/1b. The PUCCH format        1a/1b is transmitted on the SCell UL carrier.    -   For a TDD pSCell, if no (E)PDCCH corresponding to PDSCH on other        cells in the PUCCH cell group is received and PDSCH is received        on the pSCell in only one DL subframe where the DAI value is set        to ‘1,’ fall back to PUCCH format 1a/1b. The PUCCH format 1a/1b        is transmitted on the SCell UL carrier.

In this regard, FIGS. 15A and 15B illustrate a fallback procedureperformed by the wireless device 16 according to some embodiments of thepresent disclosure. This fallback procedure implements the conditionsfor fallback to PUCCH format 1a/1b provided above. As illustrated, PUCCHis transmitted on an SCell only. In order to determine whether PUCCHformat 4 should fallback to some other PUCCH format, the wireless device16 determines whether the pSCell, which in this case is one of theSCells 14 of the wireless device 16, for a PUCCH cell group for such aPUCCH transmission is desired is on an FDD carrier or a TDD carrier(step 1000). If the pSCell of the wireless device 16 is on an FDDcarrier, the wireless device 16 determines whether: (a) the wirelessdevice 16 has received no (E)PDCCH corresponding to PDSCH on any otherSCells of the wireless device 16 in the PUCCH cell group and (b) thewireless device 16 has received a PDSCH on the pSCell of the PUCCH cellgroup (step 1002). If the conditions in step 1002 are true, then thewireless device 16 decides that fallback to PUCCH format 1a/1b isappropriate and, as such, transmits PUCCH according to format 1a/1b(step 1004).

Returning to step 1100, if the pSCell of the wireless device 16 for thePUCCH cell group is not an FDD cell (i.e., if the pSCell of the wirelessdevice 16 is a TDD cell), the wireless device 16 determines whether: (a)the wireless device 16 has received no (E)PDCCH corresponding to PDSCHon any other SCell of the wireless device 16 in the PUCCH cell group and(b) the wireless device 16 has received a PDSCH on the pSCell in onlyone DL subframe where the DAI value is set to “1” (step 1006). If theconditions in step 1006 are true, then the wireless device 16 decidesthat fallback to PUCCH format 1a/1b is appropriate and, as such,transmits PUCCH according to format 1a/1b (step 1004).

If the conditions in step 1002 are false for a FDD pSCell or if theconditions in step 1006 are false for a TDD pSCell, the wireless device16 determines whether one or more conditions for fallback to PUCCHformat 3 are satisfied (step 1008). While any suitable conditions may beused, some example conditions for fallback to PUCCH format 3 for thecase where PUCCH is transmitted on the PCell 14-1 are described below.If the condition(s) for fallback to PUCCH format 3 is satisfied, thewireless device 16 decides that fallback to PUCCH format 3 isappropriate and, as such, transmits PUCCH according to format 3 (step1010). However, if the condition(s) for fallback to PUCCH format 3 isnot satisfied, the wireless device 16 decides that fallback to PUCCHformat 3 is not appropriate and, as such, transmits PUCCH according tothe new format, which again is referred to herein as format 4 (step1012).

PUCCH may fall back to PUCCH format 3 as described above in the sectionrelating to PUCCH on both PCell and SCell.

V. System Operation and Wireless Device and Base Station Embodiments

FIG. 16 illustrates the operation of the base station 12 and thewireless device 16 according to some embodiments of the presentdisclosure. As illustrated, the base station 12 transmits DLtransmissions to the wireless device 16 (e.g., on PDSCH) on one or morecells (e.g., the PCell 14-1 and, in some cases, one or more of theSCells 14-2 through 14-32). The wireless device 16 determines the PUCCHformat for a PUCCH transmission including HARQ-ACK(s) for the DLtransmission(s) on the respective cell(s) (step 1102). The determinedPUCCH format is either PUCCH format 4 or, if the wireless device 16decides fallback is appropriate, PUCCH format 1a/1b or PUCCH format 3,as discussed above. The wireless device 16 transmits the PUCCHtransmission in the determined PUCCH format on the appropriate cell(e.g., the PCell or the pSCell) (step 1104). The base station 12receives and processes the PUCCH transmission, as will be understood bythose of ordinary skill in the art (step 1106).

FIG. 17 is a schematic block diagram of the base station 12 according tosome embodiments of the present disclosure. This discussion is equallyapplicable to other types of radio access nodes. Further, other types ofnetwork nodes may have similar architectures (particularly with respectto including processor(s), memory, and a network interface). Asillustrated, the base station 12 includes a baseband unit 18 thatincludes one or more processors 20 (e.g., Central Processing Units(CPUs), Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs), and/or the like), memory 22, and anetwork interface 24 as well as one or more radio units 26 that eachincludes one transmitters 28 and one or more receivers 30 coupled to oneor more antennas 32. In some embodiments, the functionality of the basestation 12 (or more generally the functionality of a radio access nodeor more generally the functionality of a network node) described abovemay be fully or partially implemented in software that is, e.g., storedin the memory 22 and executed by the processor(s) 20.

In some embodiments, a computer program including instructions which,when executed by at least one processor, causes the at least oneprocessor to carry out the functionality of the base station 12according to any of the embodiments described herein is provided. Insome embodiments, a carrier containing the aforementioned computerprogram product is provided. The carrier is one of an electronic signal,an optical signal, a radio signal, or a computer readable storage medium(e.g., a non-transitory computer readable medium such as memory).

FIG. 18 is a schematic block diagram of the base station 12 according tosome other embodiments of the present disclosure. The base station 12includes one or more modules 34, each of which is implemented insoftware. The module(s) 34 provide the functionality of the base station12 described herein. For example, the module(s) 34 may include one ormore modules 34 to receive and processes PUCCH transmissions from thewireless device 16.

FIG. 19 is a schematic block diagram of the wireless device 16 (e.g., aUE) according to some embodiments of the present disclosure. Asillustrated, the wireless device 16 includes one or more processors 36(e.g., CPUs, ASICs, FPGAs, and/or the like), memory 38, and one or moretransceivers 40 each including one or more transmitter 42 and one ormore receivers 44 coupled to one or more antennas 46. In someembodiments, the functionality of the wireless device 16 described abovemay be fully or partially implemented in software that is, e.g., storedin the memory 38 and executed by the processor(s) 36.

In some embodiments, a computer program including instructions which,when executed by at least one processor, causes the at least oneprocessor to carry out the functionality of the wireless device 16according to any of the embodiments described herein is provided. Insome embodiments, a carrier containing the aforementioned computerprogram product is provided. The carrier is one of an electronic signal,an optical signal, a radio signal, or a computer readable storage medium(e.g., a non-transitory computer readable medium such as memory).

FIG. 20 is a schematic block diagram of the wireless device 16 accordingto some other embodiments of the present disclosure. The wireless device16 includes one or more modules 48, each of which is implemented insoftware. The module(s) 48 provide the functionality of the wirelessdevice 16 (e.g., UE) described herein. For example, the module(s) 48include one or more transmit, or transmission, modules that operate totransmit (via an associated transmitter(s) of the wireless device 16)PUCCH transmissions according to the embodiments described herein. Themodule(s) 48 may further include a fallback module that operates to madefallback decisions for fallback of PUCCH format 4 to either PUCCH format1a/1b or PUCCH format 3 according to the embodiments described herein.

The following acronyms are used throughout this disclosure.

-   -   3GPP Third Generation Partnership Project    -   5G Fifth Generation    -   ACK Acknowledgement    -   ASIC Application Specific Integrated Circuit    -   CA Carrier Aggregation    -   CC Component Carrier    -   CN Core Network    -   CPU Central Processing Unit    -   CSI Channel State Information    -   DAI Downlink Assignment Indicator    -   DCI Downlink Control Information    -   DL Downlink    -   DMRS Demodulation Reference Signal    -   eNB Enhanced or Evolved Node B    -   EPDCCH Enhanced Physical Downlink Control Channel    -   FDD Frequency Division Duplex    -   FPGA Field Programmable Gate Array    -   GHz Gigahertz    -   HARQ Hybrid Automatic Repeat Request    -   LAA Licensed Assisted Access    -   LTE Long Term Evolution    -   LTE-U Long Term Evolution in Unlicensed Spectrum    -   MHz Megahertz    -   MME Mobility Management Entity    -   MTC Machine Type Communication    -   NACK Negative Acknowledgment    -   OCC Orthogonal Cover Code    -   PCC Primary Component Carrier    -   PCell Primary Cell    -   PDCCH Physical Downlink Control Channel    -   PDN Packet Data Network    -   PDSCH Physical Downlink Shared Channel    -   P-GW Packet Data Network Gateway    -   PRB Physical Resource Block    -   pSCell Primary Secondary Cell    -   PUCCH Physical Uplink Control Channel    -   PUSCH Physical Uplink Shared Channel    -   RAN Radio Access Network    -   RE Resource Element    -   Rel-8 Release 8    -   Rel-10 Release 10    -   Rel-11 Release 11    -   Rel-12 Release 12    -   Rel-13 Release 13    -   SCC Secondary Component Carrier    -   SCEF Service Capability Exposure Function    -   SCell Secondary Cell    -   SR Scheduling Request    -   TBCC Tail-Biting Convolutional Code    -   TDD Time Division Duplex    -   TPC Transmit Power Control    -   UCI Uplink Control Information    -   UE User Equipment    -   UL Uplink    -   WLAN Wireless Local Area Network

Those skilled in the art will recognize improvements and modificationsto the embodiments of the present disclosure. All such improvements andmodifications are considered within the scope of the concepts disclosedherein and the claims that follow.

What is claimed is:
 1. A method of operation of a wireless device in acellular communications network to transmit uplink control informationfor one or more carriers on an uplink control channel, comprising:transmitting an uplink control channel transmission using a first uplinkcontrol channel format if a first set of one or more conditions for thefirst uplink control channel format is satisfied; transmitting theuplink control channel transmission using a second uplink controlchannel format if the first set of one or more conditions for the firstuplink control channel format is not satisfied but a second set of oneor more conditions for the second uplink control channel format issatisfied; and transmitting the uplink control channel transmissionusing a third uplink control channel format if both the first second ofone or more conditions for the first uplink control channel format andthe second set of one or more conditions for the second uplink controlchannel format are not satisfied.
 2. The method of claim 1 wherein thecellular communications network is a Third Generation PartnershipProject, 3GPP, network, the first uplink control channel format isformat 1a/1b, and the second uplink control channel format is format 3.3. The method of claim 1 wherein the third uplink control channel formatis an uplink control channel format that uses a Physical Uplink SharedChannel, PUSCH, structure.
 4. The method of claim 2 wherein the thirduplink control channel format is an uplink control channel format thatuses one of a group consisting of: legacy format 3 over multiplePhysical Resource Blocks, PRBs; legacy format 3 over a single PRB withmultiple Orthogonal Cover Codes, OCCs; legacy format 3 over multiplePRBs with multiple OCCs; modified format 3 with Tail-BitingConvolutional Code, TBCC, over multiple PRBs; modified format 3 withTBCC over a single PRB with multiple OCCs; and modified format 3 withTBCC over multiple PRBs with multiple OCCs.
 5. The method of claim 2wherein the second set of one or more conditions for the second uplinkcontrol channel format comprises a condition that a required number offeedback bits for the uplink control channel transmission is less thanor equal to a threshold, M₂.
 6. The method of claim 5 wherein thethreshold, M₂, is equal to
 22. 7. The method of claim 5 wherein thefirst set of one or more conditions for the first uplink control channelformat comprises a condition that a required number of feedback bits forthe uplink control channel transmission is less than or equal to athreshold, M₁.
 8. The method of claim 7 wherein the threshold, M₁, isequal to 2 and the threshold, M₂, is equal to
 22. 9. The method of claim7 wherein the first set of one or more conditions for the first uplinkcontrol channel format further comprises a condition that feedback bitsare required only for a Primary Cell, PCell, of the wireless device. 10.The method of claim 9 wherein the threshold, M₁, is equal to
 2. 11. Themethod of claim 9 wherein the threshold, M₂, is equal to
 22. 12. Themethod of claim 2 wherein the first set of one or more conditions forthe first uplink control channel format comprise: (a) a condition thatfeedback bits are required only for a Primary Cell, PCell, of thewireless device and (b) a required number of feedback bits for theuplink control channel format is less than or equal to a threshold, M₁.13. The method of claim 12 wherein the threshold, M₁, is equal to
 2. 14.The method of claim 2 wherein the wireless device is configured with aFrequency Division Duplexing, FDD, Primary Cell, PCell, according to acarrier aggregation scheme in which the uplink control channel istransmitted on the FDD PCell of the wireless device, and the first setof one or more conditions for fallback to format 1a/1 b comprises: (a) acondition that no downlink control channel corresponding to a downlinkshared channel on any Secondary Cells, SCells, of the wireless device isreceived and (b) a condition that a downlink shared channel is receivedon the FDD PCell of the wireless device.
 15. The method of claim 2wherein the wireless device is configured with a Time DivisionDuplexing, TDD, Primary Cell, PCell, according to a carrier aggregationscheme in which the uplink control channel is transmitted on the TDDPCell of the wireless device, and the first set of one or moreconditions for fallback to format 1a/1 b comprises: (a) a condition thatno downlink control channel corresponding to a downlink shared channelon any Secondary Cells, SCells, of the wireless device is received and(b) a condition that a downlink shared channel is received on the TDDPCell in only one downlink subframe where a Downlink AssignmentIndicator, DAI, value is set to “1.”
 16. The method of claim 2 whereinthe wireless device is configured with a Frequency Division Duplexing,FDD, or Time Division Duplexing, TDD, Primary Cell, PCell, according toa carrier aggregation scheme in which the uplink control channel istransmitted on the PCell of the wireless device, and the second set ofone or more conditions for fallback to format 3 comprises: (a) acondition that the wireless device receives a Physical Downlink SharedChannel, PDSCH, only on cells within a segment of less than or equal toM₂ feedback bits in a sequence of N possible feedback bits where N>M₂and (b) a condition that no downlink control channel is received by thewireless device on any other cells.
 17. The method of claim 2 whereinthe wireless device is configured with a Frequency Division Duplexing,FDD, Primary Secondary Cell, pSCell, in a cell group according to acarrier aggregation scheme in which the uplink control channel istransmitted on the FDD pSCell, where the FDD pSCell can be either aPrimary Cell, PCell, of the wireless device or one of one or moreSecondary Cells, SCells, of the wireless device, and the first set ofone or more conditions for fallback to format 1a/1b comprises: (a) acondition that no downlink control channel corresponding to a downlinkshared channel on any SCells in a cell group is received and (b) acondition that a downlink shared channel is received on the FDD pSCell.18. The method of claim 2 wherein the wireless device is configured witha Time Division Duplexing, TDD, Primary Secondary Cell, pSCell, in acell group according to a carrier aggregation scheme in which the uplinkcontrol channel is transmitted on the TDD pSCell, where the TDD pSCellcan be either a Primary Cell, PCell, of the wireless device or one ofone or more Secondary Cells, SCells, of the wireless device, and thefirst set of one or more conditions for fallback to format 1a/1bcomprises: (a) a condition that no downlink control channelcorresponding to a downlink shared channel on any SCells in a cell groupis received and (b) a condition that a downlink shared channel isreceived on the TDD pSCell in only one downlink subframe where aDownlink Assignment Indicator, DAI, value is set to “1.”
 19. The methodof claim 2 wherein the wireless device is configured with a FrequencyDivision Duplexing, FDD, or Time Division Duplexing, TDD, PrimarySecondary Cell, pSCell, in a cell group according to a carrieraggregation scheme in which the uplink control channel is transmitted onthe pSCell, where the pSCell can be either a Primary Cell, PCell, of thewireless device or one of one or more Secondary Cells, SCells, of thewireless device, and the second set of one or more conditions forfallback to format 3 comprises: (a) a condition that downlink sharedchannels are received by the wireless device on one or more SecondaryCells, SCells, in a cell group that correspond to a segment of less thanor equal to M₂ feedback bits in a sequence of N possible feedback bits,where N>M₂ and (b) a condition that no downlink control channel isreceived by the wireless device on any other SCells in the cell group.20. The method of claim 2 wherein the wireless device is configured witha Frequency Division Duplexing, FDD, Primary Secondary Cell, pSCell,according to a carrier aggregation scheme in which the uplink controlchannel is transmitted on the FDD pSCell, where the FDD pSCell is aPrimary Cell, PCell, of the wireless device, and the first set of one ormore conditions for fallback to format 1a/1b comprises: (a) a conditionthat no downlink control channel corresponding to a downlink sharedchannel on any Secondary Cells, SCells, in a cell group is received and(b) a condition that a downlink shared channel is received on the FDDpSCell.
 21. The method of claim 2 wherein the wireless device isconfigured with a Time Division Duplexing, TDD, Primary Secondary Cell,pSCell, according to a carrier aggregation scheme in which the uplinkcontrol channel is transmitted on the TDD pSCell, where the TDD pSCellis a Primary Cell, PCell, of the wireless device, and the first set ofone or more conditions for fallback to format 1a/1b comprises: (a) acondition that no downlink control channel corresponding to a downlinkshared channel on any Secondary Cells, SCells, in a cell group isreceived and (b) a condition that a downlink shared channel is receivedon the TDD pSCell in only one downlink subframe where a DownlinkAssignment Indicator, DAI, value is set to “1.”
 22. A wireless deviceenabled to operate in a cellular communications network to transmituplink control information for one or more carriers on an uplink controlchannel, comprising: one or more transmitters; one or more processors;and memory containing instructions that are executable by the one ormore processors whereby the wireless device is operable to: transmit,via the one or more transmitters, an uplink control channel transmissionusing a first uplink control channel format if a first set of one orconditions for the first uplink control channel format is satisfied;transmit, via the one or more transmitters, the uplink control channeltransmission using a second uplink control channel format if the firstset of one or more conditions for the first uplink control channelformat is not satisfied but a second set of one or more conditions forthe second uplink control channel format is satisfied; and transmit, viathe one or more transmitters, the uplink control channel transmissionusing a third uplink control channel format if both the first second ofone or more conditions for the first uplink control channel format andthe second set of one or more conditions for the second uplink controlchannel format are not satisfied.
 23. A non-transitory computer readablemedium storing software instructions that when executed by one or moreprocessors of a wireless device cause the wireless device to: transmitan uplink control channel transmission using a first uplink controlchannel format if a first set of one or conditions for the first uplinkcontrol channel format is satisfied; transmit the uplink control channeltransmission using a second uplink control channel format if the firstset of one or more conditions for the first uplink control channelformat is not satisfied but a second set of one or more conditions forthe second uplink control channel format is satisfied; and transmit theuplink control channel transmission using a third uplink control channelformat if both the first second of one or more conditions for the firstuplink control channel format and the second set of one or moreconditions for the second uplink control channel format are notsatisfied.